Monday, March 28, 2016

March Orchid Science: Orchids in Medicine, Conservation, Evolution, and Symbiosis

Hey guys, lately I've been interested in learning more about what goes on in the world of orchid research.  I'd like to try a column where I summarize science articles about orchids.  Some of these studies are more technical than others, and I will do my best to convey their findings in an understandable manner.

As the end of March is approaching, here is a wrap-up of this month's orchid science news.


    Gastrodia elata orchid
    Photo Credit
    Qwert1234, Wikimedia commons

    Gastrodia elata is an orchid species used in Sichuan cuisine and traditional Chinese medicine. It is a rootless, leafless plant, which grows from an underground tuber that produces a flowering stalk as shown in the image above. 

    Gastrodin is a chemical compound produced by Gastrodia elata, which is responsible for some of its medicinal properties. Studies have investigated gastrodin's medical potential in a variety of contexts, including everything from anxiety to diabetes and dementia. We know that Gastrodia elata produces high levels of gastrodin during growth of juvenile tubers, but we don't know how the plant synthesizes this chemical.

    In this study, the authors used a technique called de novo transcriptome sequencing to compare gene expression levels in germinated seeds versus juvenile plants. This is the first time that anyone has done a comprehensive genetic study of this orchid. 

    The resulting data gives us information about which genes are active in Gastrodia elata at different stages of the orchid's early growth. The authors then proceeded to identify two novel genes which encode for enzymes that may be involved in the biosynthesis of gastrodin.

    Authors: Tsai CC, Wu KM, Chiang TY, Huang CY, Li SJ, Chiang YC.
    Published in BMC Genomics (March 9, 2016)
    Comparative transcriptome analysis of Gastrodia elata (Orchidaceae) in response to fungus symbiosis to identify gastrodin biosynthesis-related genes


      Epicactis orchid species examined in Jacquemyn et al 2016
      Photo Credits:
      Epicactis helleborine, by Amadej Trnkoczy (Flickr gallery)
      Epicactis are a genus of terrestrial orchids; these species are hardy and can survive in a broad range of environments. Epicactis helleborine, originally a European species, has spread across Asia, northern Africa and North America.  It is increasingly considered invasive in parts of the US, earning it the moniker "weed orchid."

      This study looked at mycorrhizal fungus communities associated with three epicactis species (Epipactis helleborineEpipactis neerlandica, and Epipactis palustris).  Many orchid species require the presence of symbiotic root fungi (mycorrhiza) throughout life for optimal growth and development. Terrestrial orchids rely on specific fungi to trigger seed germination and/or initiate development of orchid seedlings. 

      Epicactis helleborine and Epicactis neerlandica have only recently evolved to be separate species.  However, they occupy extremely different environments; E. helleborine grows primarily in forests, and E. neerlandica is found almost exclusively in coastal dunes.  E. palustris is an evolutionarily more distant species that also grows in coastal dune habitats.

      This study found a total of 105 different kinds (taxa) of mycorrhizal fungi among the roots of these three orchid species. Each orchid species had a unique mycorrhizal community. Out of the 105 types of fungus identified in the study, only 8 were shared among all three orchid species. The differences were the most pronounced between the forest-growing orchid (E. helleborine) and the two dune species (E. neerlandica and E. palustris).

      Figure 3. A. from Jacquemyn et al 2016 
      This venn diagram depicts how many taxa of mycorrhizal fungi are unique to each orchid species, and how many are shared between them.

      Authors: Jacquemyn H, Waud M, Lievens B, Brys R
      Published in Annals of Botany (March 5, 2016)
      Differences in mycorrhizal communities between Epipactis palustris, E. helleborine and its presumed sister species E. neerlandica.

      Phalaenopsis aphrodite var formosana
      Photo Credit: Orchi (wikimedia commons image)

      Pollination and seed maturation works differently in orchids than it does in most flowers.  Like most other things, it is slower.  Much slower.  In most flowers, the ovule structure and the embryo sac have fully developed by the time the flower opens.  Once a flower is pollinated, the pollen reaches the ovule within hours, fertilizing the embryo, which then develops into a seed.

      Orchid flowers, on the other hand, will not even begin developing an ovule until after pollination has occurred.  This is an energy-saving strategy by the plant, which will only put in resources to develop the ovule if pollination has already occurred.

      One consequence of this delay is that the ovule must have enough time to mature after the orchid first senses pollination. As a result, orchids can have a delay of days, or even months between pollination and fertilization. In Vanda suavis, pollen can take up to 10 months to fertilize the flower.

      The authors in this study observed the timing of pollination and fertilization in Phalaenopsis aphrodite var. foromsana. They purchased seedlings from a commercial supplier.  The orchids produced flower stalks after about 2 months of cultivation, and the first flowers opened 1-2 months after that.

      The authors hand-pollinated these flowers and observed how the flower developed in response to pollination. They found that the pollen grains did not even begin to germinate until 3 days after pollination.  After that, it took 60-65 days for the pollen to reach the ovules deep in the body of the flower, and complete fertilization.  The timing of this 2-month journey for the pollen matched the timing of ovule maturation.

      Authors: Chen JC, Fang SC


      This study looked at seed germination and seedling development of Cynorkis purpurea in a lab setting.  Cynorkis purpurea is a terrestrial orchid that generally lives only in gallery forests in the Central Highlands of Madagascar.  

      The authors of this study wanted to understand how various symbiotic fungi influence seed germination and seedling development of Cynorkis purpurea.  They collected seeds from wild orchids in Madagascar, and attempted to grow them in the lab.  Some seeds were grown in the presence of orchid mycorrhizal fungi, while other seeds were grown in conditions without fungi.

      One of the things I was struck by in this study, was how slowly orchid seeds develop, even under optimal conditions.  Panel "d" in the image below shows what a 'successfully developed' seedling looked like after 3 months of growth.  At less than 1/2 a millimeter in diameter, the seedling is still nearly microscopic.

      Figure from Rafter et al, 2016, showing the germination stages of Cynorkis purpurea seeds

      a. What a Cynorkis purpurea seed looks like before germination 
      b. A successfully germinated seed (2-4 weeks)
      c. A fully germinated orchid seed shows fungal tendrils growing along its surface 
      d. After 12 weeks, seeds grown in favorable conditions will have developed the start of a shoot

      The study found that while Cynorkis purpurea seeds do not require symbiotic fungi for germination, seedlings developed dramatically better when they were paired with symbiotic fungi. The authors compared three different genera of fungus, and found that sebacina fungi were the most effective at promoting orchid seedling development. 

      One of the control conditions, which added sucrose to the growth media to simulate the effect of fungal presence, also significantly boosted seed germination and development. 

      Authors: Rafter M, Yokoya K, Schofield EJ, Zettler LW, Sarasan V.
      Published in Micorrhiza (March 17, 2016)
      Non-specific symbiotic germination of Cynorkis purpurea (Thouars) Kraezl., a habitat-specific terrestrial orchid from the Central Highlands of Madagascar


      Example of 4 orchid species that use CAM photosynthesis
      Photo Credits:
      Dendrobium terminale, (C) by G. Meyer 1990, Swiss Orchid Foundation at the Herbarium Jany Renz. Botanical Institute, University of Basel, Switzerland.
      Crassulacean acid metabolism, or CAM photosynthesis, is an adaptation that allows some plants to conserve water in arid conditions.  It is mostly found in succulents.  However, among approximately 25,000 known species of orchids, about 10,000 are estimated to use CAM photosynthesis.  

      Photosynthesis requires that plants take in carbon dioxide (CO2) from the air. However, when a plant opens its pores (stoma) to intake carbon dioxide, it also loses water through evaporation. In order to survive in water-scarce environments, some plants have evolved a way to take in CO2 at night, when temperatures are cooler and evaporation is less of a problem.  CAM photosynthesis is a method by which some plants can accumulate and store CO2 at night for use in photosynthesis during daytime.  Plants that use CAM photosynthesis can require as much as 80% less water than other kinds of plants.

      Scientists are interested in studying plants which use CAM photosynthesis, because it can be useful for developing drought-resistant crops.  This study did the first comparative genetics look at CAM in orchids. The authors examined CAM-related genes from 4 orchid species that had the CAM adaptation (Cymbidium atropurpureum,  Phalaenopsis mannii, Phalaenopsis equestris, and Dendrobium terminale), 9 orchid species that did not have CAM, and 12 other non-orchid species.

      The authors concluded that CAM may have evolved in orchids through changes in expression level of a few key genes involved in carbon fixation during photosynthesis.

      Authors: Zhang L, Chen F, Zhang GQ, Niu S, Xiong JS, Lin Z, Cheng ZM, Liu ZJ
      Published in The Plant Journal (March 9, 2016)
      Origin and mechanism of crassulacean acid metabolism in orchids as implied by comparative transcriptomics and genomics of the carbon fixation pathway.

      Sunday, March 27, 2016

      Using rooting hormone to rescue rootless orchid

      Rlc (Port Royal Sound 'Big Red' X Chia Lin 'Shinsu #1')
      This is my sickest orchid that is still alive after the long drought of neglect.  The orchid is in a sad little state, compared to my last post about it, almost 4 years ago

      I've found that severe underwatering is just as capable of killing off orchid roots as overwatering.  A dehydrated orchid will put out new growths, but then lose them before they have a chance to fully mature.  In the picture above, you can see two nubs of pseudobulbs, which lack a leaf at the tip.  The leaves had rotted off when I neglected to water the orchid during a critical period of growth.

      Two new growths at base of cattleya orchid

      Looking closer at the base of the orchid, I can spot what looks like two new growth starts.  They look a little like purple onions.  I am hoping, that with more diligent care, I can nurse these two growths into maturity.

      Normally, it seems that in a struggling orchid, new growths must develop first, and then they can put out a set of new roots.  Old pseudobulbs can provide water storage and nutrients to support the orchid, but do not generally produce active growth.  I am curious whether I could trigger some more growth activity.  I purchased a small amount of rooting hormone, to test out whether it can help spur better recovery for the orchid.
      Orchid covered in rooting powder
      The instructions on the rooting powder indicated to dip the base of the plant directly into the powder, and then to pot.  I padded the rooting powder along the base of the plant (though mostly trying to avoid the new growths themselves).  Afterwards, I returned the orchid to the smallest size plastic pot that I own.

      Now, the onus is on me to remember to water the orchid every 3 days, so that it never experiences extended periods of dryness.  I'll check back in a few weeks to see whether the rooting hormone had any effect.  In the meantime, with two new growth starts, diligence in watering should be all that I really need to assure survival.

      Saturday, March 19, 2016

      The many faces of Oncostele Wildcat

      Oncostele Wildcat
      This is Oncostele Wildcat. It is an orchid hybrid with a wide variety of color patterns.  The five flowers in the image above are ones that I've personally photographed during different years of the New York Orchid Show.  However, searching online for 'Oncostele Wildcat' reveals an even broader range of flower shapes and colors.

      This hybrid, which was registered in 1992, is widely popular, and has a great diversity of flowers.  I had a lot of fun researching its background.  Digging into the ancestry of Oncostele Wildcat is like going into the very history of orchid breeding itself.

      Check out this crazy lineage tree.
      Geneology of Oncostele Wildcat

      [Side note: I'm having a difficult time getting these lineage trees to look sharp in preview mode, especially on mobile.  Blogger does not have an option for uploading SVG files.  Anyone have a suggestion how to best upload detailed diagrams without losing resolution?]

      Things start out fairly normal; Oncostele Wildcat is a cross between Oncostele Rustic Bridge and Oncidium Crowborough.  However, after that things get complicated and the genealogy tree turns into a complicated web of crosses and back-crosses. In the parentage of Oncidium Crowborough are 6 generations of orchid hybrids, dating as far back as 1898!

      For reference, the mid-1800's were the peak of Victorian era orchid mania, when explorers traveled around the world to collect wild orchids.  The first known orchid hybrid was made in 1853 (Calanthe Dominii [Calanthe masuca x Calanthe furcata]. Only 40 years later, the hybrids at the top of Wildcat's genealogy tree may be some of the first oncidium crosses ever made.

      Without a history book on orchid cultivation at my disposal, I could not definitively figure out what was the first registered oncidium hybrid. However, this patent references a cross by Vuylsteke made in 1898 as the first time an oncidium was hybridized in cultivation.  The patent doesn't specify the cross, which could be referring to either Oncidium Ardentissimum or Oncidium Rolfeae. However, both of these very early hybrids are in the family tree of Oncostele Wildcat. 

      Oncostele Wildcat is made from 9 orchid species: 1 Rhynchostele, and 8 Oncidiums.

      Rhynchostele uroskinneri, Oncidium fuscatum, Oncidium leucochilum, Oncidium alexandre, Oncidium spectatissimum, Oncidium nobile, Oncidium luteopurpureum, Oncidium hallii, Oncidium harryanum
      Progenitors of Oncostele wildcat

      Photo credits: 
      Oncidium fuscatum by Eduardo A. Pacheco (Flickr gallery)
      Oncidium leucochilum by Arne and Bent Larsen Orchid collection
      Oncidium hallii by Andreas Kay (Flickr gallery)
      Oncidium harryanum by Diego Rodriguez (Flickr gallery)
      Note: Oncidium alexandre is also commonly referred to as Oncidium crispum.

      The genealogy tree for Oncostele Wildcat shows that Oncidium alexandre was crossed into this hybrid 6 different times.  It looks like the overall flower shape of Oncostele Wildcat and Oncidium alexandre are highly similar.  Another overachiever, Oncidium spectatissimum, was bred into the cross 3 times; it has many similar dark and bright orange markings as Oncostele Wildcat. However, with a hybrid this complicated, it may be futile to try and parse out how each individual species contributed to the end result.

      And finally, these are the larger versions of the photographs that comprised my title image.
      Oncostele Wildcat
      Oncostele Wildcat 'Carmela'
      Oncostele Wildcat 'Cheetah'
      Oncostele Wildcat 'Everlasting'
      Oncostele Wildcat 'Silver Cool Room'

      Saturday, March 12, 2016

      Colmanara Masai Red

      Colmanara Masai Red
      This richly colored orchid is an old favorite from the New York Orchid show that makes an appearance every year.  In fact, I first photographed it back in 2013, as part of my Oncidiums of the 2013 Orchid Show post. 

      The flowers are so showy, that I thought for sure this would be another very complicated hybrid. Surprisingly, Colmanara Masai Red is a simple cross between two species.  This orchid was first registered in 2007.

      Colmanara Masai Red is a hybrid between Rhynchostele bictoniensis (seed parent), and Oncidium cariniferum (pollen parent).
      Parentage of Colmanara Masai Red 
      Photo Credits:
      Rhynchostele bictoniensis photo by Stefano (see their Flickr photo gallery)
      Oncidium Cariniferum photo (C) Eric Hunt (see his orchid photo website, also, Flickr gallery)
      I can definitely see reflections of both parent species in Colmanara Masai Red.  IOSPE lists a "brown and purple" form of Rhynchostele bictoniensis, which has a more similar hue to Colmanara Masai Red.

      Sunday, March 6, 2016

      Bratonia Kauai's Choice

      Bratonia Kauai's Choice
      It has been a long hiatus for this blog.  I never forgot it, but at the same time life was happening at such a pace, that there never seemed quite enough time to start it up again properly.  However, if there is one thing that could draw me back into photographing, writing and thinking about orchids, it would be the yearly spectacle that is the New York Orchid show.  For a month at the very beginning of spring, the Bronx Botanical Garden is filled with thousands of blooming orchids.  I have never missed an opportunity to go. 

      In a change from my previous Orchid Show postings, I'd like to really focus in detail on the flowers I've photographed, and take a chance to learn more about where these beautiful orchids came from.  I'll still put up the full gallery of photos from the Orchid Show on my Facebook page.  Meanwhile, I will use the blog to learn about the orchids I've photographed.

      So with no more ado, I present Bratonia Kauai's Choice.

      These large spider-like blooms are among the very first orchids you meet upon entering the conservatory at the Bronx Botanical Garden.  They are a perennial fixture each year at the orchid show.  Bratonia Kauai's Choice (formerly known as Miltassia Kauai's Choice) is a cross between Brassia arcuigera (a species) and Bratonia Aztec (a hybrid). This hybrid was registered in 1998 by Yamada Nursery in Hawaii.

      Parentage of Bratonia Kauai's Choice
      Photo credits

      Bratonia Aztec by Arne and Bent Larsen orchid collection (Link to Wikimedia gallery)
      What jumps out immediately, is how the elongated shape of the petals comes from the Brassia side of the lineage.  Meanwhile, the lip of the Kauai's Choice bears a resemblance to Bratonia Aztec.  However, neither parent carries the purple coloration seen in Kauai's Choice, implying that the purple color is hidden further back in this orchid's ancestry.
      Progenitors of Bratonia Kauai's Choice

      I looked up the geneaology of this orchid, and it was like diving into a rabbit hole. In total, 10 different orchids, including 5 unique species  (labeled in green) were used in the making of this hybrid. 
      Interesting side note: Miltonia bluntii (lower case 'b') is a naturally occurring hybrid between M. clowesii and M. spectabilis.  Meanwhile Miltonia Bluntii (upper case 'B') refers to the man-made cross between the two species registered in 1879

      Here are the original species that went into creating Bratonia Kauai's Choice. 

      Species that went into making Bratonia Kauai's Choice

      Photo Credits:

      Side note: I was interested to learn that Miltonia spectabilis has a purple variant called morelliana.  I am curious whether the variant might have been used at any point in the making of Bratonia Kauai's choice, although I could not find evidence indicating either way.

      Looking at the species which went into making Bratonia Kauai's Choice, it appears that the orchid gained purple coloration from its Miltonia ancestors, and the general flower shape of its two Brassia progenitors.  

      I really did not anticipate that Bratonia Kauai's Choice would end up being such a complex hybrid.  Hopefully my next project will be a shorter undertaking.